An early March day sits outside my office window, silent, grey and still. No leaves rustle in the breeze, no birds sing from the tree tops, and no bees buzz in the raingarden. Though it is gloomy today, the days are growing steadily warmer and I know that spring’s burst of green life is just around the corner. Soon, I’ll hear the first trill of the red-winged blackbird in the cattails. Soon too, the insects will spring to life again, reclaiming the landscape we mistakenly thought to be ours.
We humans hold inconsistent opinions about insects. We adore the graceful beauty of a butterfly, admire the hard-working virtue of a honeybee, and despise the very existence of cockroaches, mosquitoes, and countless other insects. Is it possible to plant a pollinator-friendly landscape without extending an invitation to other insects as well? Would we want to if we could?
There are thousands of insect species in Minnesota, some that we consider pests and others that we consider beneficial. With the exception of non-native introduced species like emerald ash borer, however, predator-prey interactions, as well as limited food supplies, usually prevent any one species from growing out of control. Swallows and jumping spiders eat houseflies, while dragonflies and bats eat mosquitoes. Ladybug beetles eat aphids, mealybugs and spider mites, while assassin bugs, big-eyed bugs and syrphid fly larva eat aphids, caterpillars, leafhoppers and mealybugs. The trichogramma wasp larvae parasitize the eggs of over 200 pest insects, devouring their growing bodies from the inside out. What a way to imagine your insect enemies dying!
In the book, Bringing Home Nature: How You Can Sustain Wildlife With Native Plants, Douglas Tallamy advises that we plant trees, shrubs and flowers that are native to our area in order to intentionally attract more insects to our yards, both to provide food for birds and wildlife and to keep pest insects from running amok. Nearly all songbirds rely on insects and spiders for food during spring, summer and fall; the reason they fly south during the winter is to find food, not escape the cold. Tallamy focuses on the benefits of native trees and shrubs, which nurture an astounding array of larval insects, and in turn, hundreds of bird species as well. Bur oak and white oak attract 518 species of larval insects, creating a veritable bird buffet. Smaller trees like serviceberry, redosier dogwood and nannyberry hostover 100 species of larval insects and produce berries for birds to eat as well as. Even perennial wildflowers like aster, wild strawberry and goldenrod support close to 100 species of larval insects each.
Local author Heather Holm explores insect interactions for 31 flowering prairie plants, 18 woodland plants, and 18 wetland plants in her guidebook, Pollinators of Native Plants: Attract, Observe and Identify Pollinators and Beneficial Insects with Native Plants. One example, wild bergamot (Monarda fistulosa – also known as bee balm), is one of the best forage plants for bumble bees. Bergamot also provides nectar for honeybees, black sweat bees, mason wasps, great black wasps, eastern tiger swallowtail butterflies, silver spotted skipper butterflies, monarch butterflies, great spangled fritillary butterflies, moths, snout moths, hummingbird clearwing moths, long-horned bees, cuckoo bees, green sweat bees, wool carder bees, small resin bees, leafcutter bees, and sweat bees. And, that’s not all! Soldier beetles – a predatory insect that eats aphids, fly larvae, small caterpillars, beetle larvae, and grasshopper eggs – also feed on bergamot nectar. Bee flies, another predatory insect, feed on bergamot nectar, before following bees and wasps back to their ground nests and laying their eggs at the entrance. When the bee fly larvae later emerge, they eat the bee and wasp larvae – another example of nature keeping nature in check. But, that’s still not all! In addition to providing nectar for all those different kinds of insects, the bergamot plant itself is the larval host for hermit sphinx moths and snout moths.
Coincidentally, many of the native trees, shrubs and flowers that provide food for pollinators and habitat for birds also help to keep the St. Croix River and nearby lakes clean. These plants capture large quantities of rain and melting snow before it causes erosion or runoff pollution. Their deep roots also help to stabilize crumbling river bluffs, stream banks and lakeshores, as well as breaking up compacted soil in residential yards.
Begin planning today for planting projects later this spring. Order low-cost trees now to pick up on April 22-23 (www.mnwcd.org) or scroll through www.BlueThumb.org for a list of local native plant retailers near you. Check out www.mnwcd.org/events as well for information about upcoming landscaping workshops, including the Master Gardener Spring Gardening Program on Sat., March 26, 8am-noon at the Stillwater Area High School.